Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Atrial Function, Left”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
PubMed1997

Contribution of left atrial pressure and dimension to signal-averaged P-wave duration in patients with chronic congestive heart failure.

In a group of patients with chronic heart failure, a longer P-wave duration on signal-averaged electrocardiogram was found in those patients with higher pulmonary capillary wedge pressure, whereas the left atrium end-systolic diameter was not significantly different. Furthermore, an acute reduction in pulmonary capillary wedge pressure induced by sodium nitroprusside infusion was associated with a reduction in P-wave duration.

Adult↗
PubMed2004

Left atrial volume and the risk of paroxysmal atrial fibrillation in patients with hypertrophic cardiomyopathy.

Paroxysmal atrial fibrillation (PAF) is a common complication of patients with hypertrophic cardiomyopathy, often leading to acute or progressive heart failure and cerebral infarction. We assessed the echocardiographic data of 141 consecutive patients with hypertrophic cardiomyopathy, with and without PAF. In all, 31 patients (22%) had a history of PAF with spontaneous conversion to in sinus rhythm. Left atrial volume and left atrial volume indexed to body surface area were significantly increased for patients with PAF compared with those without PAF. Maximum left atrial volume was the most sensitive and specific parameter for the occurrence of PAF in patients with hypertrophic cardiomyopathy.

Atrial Fibrillation↗
PubMed2002

Atrial fibrillation recurrence after internal cardioversion: prognostic importance of electrophysiological parameters.

OBJECTIVE: To evaluate the clinical and electrophysiological determinants of arrhythmia recurrence in patients undergoing internal atrial cardioversion for chronic atrial fibrillation (AF). SETTING: Tertiary cardiac referral centre. METHODS: 101 consecutive patients with failed external cardioversion or AF > or = 1 year underwent internal atrial cardioversion; once stable sinus rhythm (SR) was obtained, electrophysiological study was performed in 73 patients (72%) who gave informed consent. Patients were then followed on antiarrhythmic treatment. RESULTS: 101 consecutive patients underwent internal atrial cardioversion in the period 1996-1999 with 100% conversion to SR; prophylactic antiarrhythmic treatment was flecainide (52%), amiodarone (37%), and sotalol (11%). Average follow up at first AF recurrence was 18.4 (14.4) months (range 0.1-49.8 months); persistence of SR was observed in 72/101 (72%) patients. By logistic regression, AF duration (odds ratio (OR) 1.07, 95% confidence interval (CI) 1.01 to 1.13) and a lower sinus rate at discharge on antiarrhythmic drugs (OR 0.92, 95% CI 0.85 to 0.99) were independent predictors of AF recurrence, whereas age, New York Heart Association functional class, left atrial dimensions, and left ventricular ejection fraction were not predictive of arrhythmia recurrence. When electrophysiological parameters were added to the statistical model in 73 patients, a shorter atrial effective refractoriness (OR 1.04, 95% CI 1 to 1.08) and an abnormal relation of atrial effective refractoriness to cycle length (OR 31, 95% CI 3.7 to 266) were also independent predictors of AF recurrence at follow up, beyond AF duration and heart rate at discharge. CONCLUSIONS: Patients with failed external cardioversion or long lasting AF may benefit from internal atrial cardioversion and antiarrhythmic treatment to keep SR at long term; electrophysiological study may identify patients at the highest risk of arrhythmia recurrence. Although preservation of SR seems unlikely for AF duration > 3 years, a consistent minority of this subgroup (38%) may benefit from this approach.

Adult↗
PubMed1994

Global and regional haemodynamic effects of urapidil in conscious dogs with chronic coronary artery occlusion.

The haemodynamic effects of urapidil, an alpha 1-antagonist with central serotoninergic properties, were studied in an experimental canine model of chronic ischaemic heart disease. Global and regional haemodynamic recordings were made in conscious dogs with ameroid-induced single vessel coronary artery occlusion. Three intravenous bolus-infusion doses of urapidil (0.1 mg kg-1 + 0.3 mg min-1; 0.5 mg kg-1 + 1.5 mg min-1; 2.5 mg kg-1 + 7.5 mg min-1) were given on separate occasions in 12 animals. Regional blood flows were measured with radioactively labelled tracer microspheres. The effects of urapidil and dipyridamole, a powerful arteriolar vasodilator, on regional myocardial blood flow distribution to normal and collateral-dependent myocardium were compared. Urapidil caused a dose-dependent reduction of arterial blood pressure. There was moderate tachycardia and decreased left atrial filling pressures at the higher doses. Urapidil was a much weaker coronary vasodilator than dipyridamole. Dipyridamole caused maldistribution of intercoronary and transmural flows (endo-to-epicardial flow ratio in collateral-dependent regions from 1.35 +/- 0.07 to 0.7 +/- 0.13 and flow ratio between collateral-dependent and normal regions from 1.09 +/- 0.03 to 0.57 +/- 0.14). Urapidil preserved blood flow to both regions. Urapidil did not affect systolic wall thickening fraction in normal or ischaemic regions of the heart. Renal (+16%) and splanchnic perfusion (+45%) increased during urapidil infusion. Urapidil preserves myocardial function and perfusion and increases renal and intestinal blood flow in dogs with chronically ischaemic hearts.

Adrenergic alpha-Antagonists↗
PubMed1998

Effects of U-50,488H on isolated atria from rats chronically treated with the kappa-opioid agonist, U-50,488H.

The present investigation was aimed at determining if chronic activation of kappa- or mu-opioid receptors induce development of tolerance and dependence to kappa-opioid agonists on the isolated left atria of the rat. Tolerance to a kappa-agonist (specific tolerance) was induced by chronic administration of U-50,488H, a selective kappa-agonist (15 mg kg(-1) i.p. twice a day for 4 days). The animals were rendered tolerant to morphine by subcutaneous implantation of morphine pellets (75 mg per pellet) for 7 days. Tolerance to U-50,488H was observed after its chronic administration and was revealed as a rightward shift of the concentration-response curve, it was accompanied by a decrease in the maximum response and in the slope. Preparations from morphine-treated rats were not tolerant to the selective kappa-agonist, that is, there was no cross-tolerance between mu- and kappa-agonists. Dependence to the kappa-agonist was tested by administration in the organ bath of Mr-2266 (preferential kappa-antagonist) or nor-binaltorphimine (nor-BNI; selective kappa-antagonist). The administration in the organ bath of the kappa-antagonists Mr-2266 or nor-BNI to preparations from U-50,488H-treated rats induced an increase in atrial force of contraction. In contrast, the administration of the kappa-antagonists to preparations from control rats induced a decrease in atrial force of contraction. These findings demonstrate that left atria from chronically U-50488H-treated rats exhibit tolerance to the negative inotropic effects of U-50,488H as well as opioid withdrawal after nor-BNI.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1996

Modeling regional myocardial flows from residue functions of an intravascular indicator.

The purpose of the present study was to determine the accuracy and the sources of error in estimating regional myocardial blood flow and vascular volume from experimental residue functions obtained by external imaging of an intravascular indicator. For the analysis, a spatially distributed mathematical model was used that describes transport through a multiple-pathway vascular system. Reliability of the parameter estimates was tested by using sensitivity function analysis and by analyzing "pseudodata": realistic model solutions to which random noise was added. Increased uncertainty in the estimates of flow in the pseudodata was observed when flow was near maximal physiological values, when dispersion of the vascular input was more than twice the dispersion of the microvascular system for an impulse input, and when the sampling frequency was < 2 samples/s. Estimates of regional blood volume were more reliable than estimates of flow. Failure to account for normal flow heterogeneity caused systematic underestimates of flow. To illustrate the method used for estimating regional flow, magnetic resonance imaging was used to obtain myocardial residue functions after left atrial injections of polylysine-Gd-diethylenetriaminepentaacetic acid, an intravascular contrast agent, in anesthetized chronically instrumental dogs. To test the increase in dispersion of the vascular input after central venous injections, magnetic resonance imaging data obtained in human subjects were compared with left ventricular blood pool curves obtained in dogs. It is concluded that if coronary flow is in the normal range, when the vascular input is a short bolus, and the heart is imaged at least once per cardiac cycle, then regional myocardial blood flow and vascular volume may be reliably estimated by analyzing residue functions of an intravascular indicator, providing a noninvasive approach with potential clinical application.

Animals↗
PubMed2002

Rare chronic gastric volvulus associated with left atrial and mediastinal compression.

We report a case of chronic gastric volvulus associated with left atrial compression in a 75-year-old woman who presented with chest pain, shortness of breath, and hypotension after elective hemiarthroplasty of the left hip. The patient's medical history included a paraesophageal hernia and gastric volvulus diagnosed in 1997 but left untreated. The present diagnosis of gastric volvulus was made on the basis of a chest radiograph and subsequent computed tomography. Echocardiography showed the volvulus compressing the left atrium. Surgery to repair the defect was successful, and there were no operative or postoperative complications. A review of the world medical literature revealed that gastric volvulus is rarely reported to cause hemodynamic compromise or compression of the heart and mediastinal structures.

Aged↗
PubMed2002

[Open heart radio frequency left atrial compartmentation during mitral valve surgery: an alternative to the labyrinth procedure?].

The authors report their experience of radiofrequency left atrial compartimentation during open heart mitral valve surgery on 37 patients with a 42 +/- 12 months history of atrial fibrillation. The preoperative left ventricular ejection fraction was 62 +/- 8%; the left atrial diameter was 59 +/- 11 mm. The mean operative time was 245 +/- 60 minutes, which included 19 +/- 5 minutes for the ablation procedure. There were 2 early postoperative deaths and 2 deaths from non-cardiac causes at 3 and 6 months. The left ventricular ejection fraction and left atrial dimension were significantly decreased at the time of hospital discharge (54 +/- 12% and 51 +/- 7 mm respectively) (p < 0.01). After an average follow-up of 1 year, 81% of patients were free of atrial fibrillation: 6 patients had undergone DC cardioversion and 1 had a dual-chamber pacemaker. Patients in sinus rhythm after the ablation were associated with shorter periods of atrial fibrillation and smaller left atrial dimensions postoperatively than those who remained in fibrillation. The authors conclude that radiofrequency compartimentation of the left atrium associated with antiarrhythmic therapy can interrupt atrial fibrillation in 81% of patients at 1 year: the ablation procedure takes only 8% of the operation time. Predictive factors of success of ablation should be defined to determine which patients benefit most from this technique.

Adolescent↗
PubMed1994

[A case of successful operation of left atrial myxoma causing cerebral embolism].

The authors describe the case report of a young woman in whom a left atrial myxoma causing cerebral embolism was diagnosed by echocardiography. On the ninth day after the development of neurologic symptoms the tumor was excised by an emergency intervention. After the operation the condition of the patient improved considerably. In connection with the case the authors underline the role of echocardiography in the detection of sources of embolism.

Adult↗
PubMed1991

Left ventricular function in acute non-ischaemic mitral regurgitation.

Acute non-ischaemic mitral regurgitation (MR) has recently generated considerable interest because of its causal relationship to ruptured chordae tendineae and infective endocarditis, advances in its diagnosis by echo Doppler studies, and its management by afterload reduction and reconstructive surgery. It is fundamentally different from chronic MR because the previously normal, unprepared left ventricle (LV) and left atrium (LA) confront a sudden dramatic increase in volume. As the normal-sized left atrium suddenly receives a marked regurgitant flow, its pressure rises and is transmitted into the pulmonary capillaries causing pulmonary congestion and oedema. At onset, the LV function is usually well preserved and the pulmonary oedema does not reflect LV failure. In acute MR, the LV empties into the left atrium, thus reducing its radius and its systolic pressure, resulting in a decline in wall tension according to Laplace's law. With a reduction in LV wall tension, there is a marked increase in contractile shortening with marked increase in total LV output. The left ventricle may fail early in acute severe MR because it is forced to dilate rapidly before hypertrophy can occur, whereas in chronic MR both the LV diastolic volume and mass increase proportionately. With chronic persistence of MR, LV dysfunction and failure occur as a manifestation of the 'cardiomyopathy of overload'. Fortunately because of the low energy cost per unit of work in shortening, as opposed to that used for tension development, there is only a slight increase in myocardial oxygen consumption in acute MR. In patients with LV failure secondary to acute MR, the ejection fraction may be only slightly decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1993

Atrial and arterial baroreceptor influences on the circulatory response to acute changes in renal perfusion.

We have recently reported a neurally mediated reflex increase in hindlimb vascular resistance associated with an acute decrease in renal perfusion pressure in the chloralose-urethane-anesthetized rabbit. The present study was designed to investigate the influence of this reflex in the body's integrated response to circulatory disturbances by investigating the influence of carotid baroreceptor and left atrial receptors on this reflex and assessing the effect of acute changes in renal perfusion on the heart. Interaction of the renal-generated reflex with carotid baroreceptors was investigated by independent perfusion of the carotid sinus region. Responses in hindlimb perfusion pressure, at constant flow, to changes in renal perfusion were greatest with the carotid sinus perfusion pressure (CSP) low (27 +/- 4 mmHg (1 mmHg = 133.3 Pa) increase in hindlimb pressure at low CSP vs. 19 +/- 3 mmHg increase at normal CSP) and were inhibited with maximum carotid stimulation. Partial mitral obstruction, resulting in left atrial distension and atrial receptor stimulation, attenuated the hindlimb vascular response. The increase in hindlimb pressure under control conditions was 34 +/- 10 mmHg compared with 20 +/- 5 mmHg during atrial receptor stimulation. However, acute reduction of renal perfusion pressure did not result in any changes in heart rate, cardiac output, or inotropic state. It appears that both atrial and arterial baroreflexes modify the reflex change in hindlimb vascular resistance associated with acute alterations of renal perfusion.

Animals↗
PubMed1996

The clinical case report: a tool for hypothesis generation.

The clinical case report is generally limited to a description of unusual examples of the complications of disease or responses to therapy. However, it can also be used to present novel hypotheses which have been derived from individual cases. Two examples of this latter genre are presented and updated. These are Syndrome X and the stiff left atrial syndrome. In both instances, general and novel formulations were derived from single cases. With respect to Syndrome X, a hypothesis was generated that the chest pain and ST abnormalities in these patients represent excess activation of adenosine A1 receptors in the absence of myocardial ischemia. With respect to the stiff left atrial syndrome, recognition of the first case led to the recognition of the problem in many others. Now, a variant of the syndrome has been recognized in which mitral regurgitation is also present. In addition, the possibility that tricuspid annuloplasty may rescue patients dying of cardiac cachexia due to right heart failure caused by combined pressure and volume overload of the right ventricle is outlined.

Atrial Function, Left↗
PubMed1998

Comparison of automatic boundary detection and manual tracing technique in echocardiographic determination of left atrial volume.

Previous reports have indicated that echocardiography with automatic boundary detection (ABD) is useful for the noninvasive estimation of left ventricular volume. However, few data exist regarding the measurement of left atrial (LA) volume, which also provides pivotal information in the clinical setting. Therefore, the feasibility of LA volume measurement by ABD in comparison with the manual tracing using modified Simpson's method (SM) was evaluated. Fifty-nine patients with coronary artery-disease with sinus rhythm were examined. Using ABD, a region of interest was set around the LA border and mitral annulus from an apical four-chamber view. The maximal and minimal LA volume (Vmax and Vmin) were measured from the volume waveform. Using the SM, the maximal and minimal LA volume were measured by the manual tracing on frozen frames at the apical four-chamber view. The ABD displayed a curve of LA volume change that consisted of passive emptying, diastasis, and active emptying phases during the left ventricular diastolic period. Under these conditions, the Vmax and Vmin were 43.7 +/- 11.2 ml and 21.1 +/- 7.6 ml, respectively, yielding the volume change of 22.6 +/- 6.0 ml. By the SM, Vmax and Vmin were 43.1 +/- 9.9 ml (r = 0.94, p < 0.0001, y(ABD) = 0.91x (SM) + 3.6) and 22.0 +/- 9.0 ml (r = 0.91, p < 0.0001, y = 0.94x + 0.7), respectively, and the volume change was 22.8 +/- 6.1 ml (r = 0.82, p < 0.0001, y = 0.84x + 3.8). These results indicate that the ABD from the apical four-chamber approach could provide an accurate estimation of LA volume change, suggesting the potential value of this method in assessing LA function, although some technical difficulties need to be further overcome.

Adult↗
PubMed2003

Cardiac-specific overexpression of human beta2 adrenoceptors in mice exposes coupling to both Gs and Gi proteins.

1. Left atrial strips from transgenic (TG4) mice with cardiac-specific overexpression ( approximately 200-fold) of the beta(2) adrenoceptor (beta(2)AR) were isolated, and their isometric force of contraction (F(c)) in response to electrical stimulation was measured. 2. The betaAR agonist isoprenaline elicited negative inotropic responses in all left atrial strips; in 6/11 preparations, it also had a small positive inotropic effect. This 'up-phase' was observed from 0.1 to 10 nM, with the 'down-phase' occurring at higher concentrations. Both phases were mediated by beta(2)AR, as shown by their sensitivity to the beta(2)AR antagonist ICI-118,551 (100 nM; pA(2) 8.60+/-0.07, 8.45+/-0.19, for 'up-phase' and 'down-phase,' respectively), but not the beta(1)AR antagonist CGP-20712A (100 nM). Conversely, nontransgenic littermate preparations responded to isoprenaline treatment solely by an increase in F(c), which was beta(1)AR-mediated. 3. Pretreatment of left atrial strips with either 10 nM isoprenaline or 1 mM 8-bromo-cAMP significantly attenuated the TG4 'up-phase', while having no effect on either the TG4 'down-phase' or the littermate controls' responses. B. pertussis toxin treatment of the animals prevented isoprenaline's negative inotropic effects in TG4 preparations, but had no effect in littermate controls. 4. The findings imply that the responses of TG4 left atrium to isoprenaline are because of beta(2)AR coupling to G(s) and G(i) proteins, consistent with the model of Daaka et al., in which protein kinase A phosphorylation of the beta(2)AR causes a switch from G(s) to G(i) protein coupling.

Adrenergic beta-Antagonists↗
PubMed1998

Risk stratification for recurrent tachyarrhythmias in patients with paroxysmal atrial fibrillation and flutter: role of signal averaged electrocardiogram and echocardiography.

The value of signal-averaged P-wave electrocardiogram and echocardiography for predicting recurrent atrial tachyarrhythmias was prospectively investigated in 60 patients presenting with paroxysmal atrial fibrillation or flutter. All patients were followed up for 1 year after restoration of sinus rhythm. A stepwise discriminant function analysis was used to identify variables predicting recurrent atrial tachyarrhythmias. Analyzed variables included signal-averaged P-wave duration in 3 bipolar orthogonal leads (X,Y,Z) and their vector magnitude, as well as left and right atrial dimensions and volumes. During follow-up, 25 patients had recurrent atrial tachyarrhythmias, while 35 did not. Using discriminant function analysis, the left atrial antero-superior dimension was found to be the only variable predicting the recurrence of atrial tachyarrhythmias (p < 0.0038) and was able to correctly classify 65% of the study patients. It was concluded that, in patients with paroxysmal atrial fibrillation or flutter, the traditionally used determination of left atrial dimension was the variable most closely associated with a high risk for recurrent tachyarrhythmias. The signal-averaged P-wave duration did not improve tachyarrhythmia prediction.

Aged↗
PubMed1990

[Trans-esophageal stimulation of the heart: electrophysiological properties of the heart of healthy subjects IV].

The aim of the study to compare left atrial and ventricular electrophysiological properties determined by transesophageal stimulation with those of right atrium and ventricle measured by other authors using transvenous cardiac stimulation. 45 healthy persons (13 females and 32 males) with average age 37 years underwent the study. Transesophageal pacemaker SP-5 made by TEMED and an universal diagnostic electrode for atrial as well as ventricular stimulation were used to obtain ++noise-free recordings. ECG was recorded by 6-channel Mingograph 61 (Simens-Elema) with a paper speed - 100 mm/s. Left atrial effective refractory period (ERP LA), left ventricular effective refractory period (ERP LV), ERP of a-v conduction system measured from atrium and ventricle (ERP AVCS A, ERP AVCS R) were determined basing on generally acceptable criteria. Parameters were measured during sinus rhythm as well as atrial and ventricular stimulation with a pacing cycle length of 700 and 500 ms. There were also determined maximal antero- and retrograde 1:1 conduction via a-v node and a-v conduction time in both directions during atrial and ventricular pacing with a cycle length of 600 ms. No retrograde a-v conduction was stated in 33% of patients. Shortening of left atrial and ventricular effective refractory periods was respective to shortening of pacing cycle length from 700 to 500 ms: ERPLA-256-245-235 ms, for ERPLV-278-248-241 ms for ERP AVCS A-301, 405, 360 ms and for ERP AVCS R during sinus rhythm-312 ms. Maximal anterograde 1:1 a-v conduction was 162/min and retrograde one 156/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

A pharmacological investigation of the contribution of muscarinic receptor-linked potassium channels to the reversal by carbachol of positive inotropic responses of rabbit left atrium to cyclic AMP-generating agents.

The purpose of the present study was to investigate whether the reversal by carbachol of positive inotropic responses of left atria to forskolin and isobutylmethylzanthine (IBMX) is related to the ability of carbachol to open potassium channels. Pretreatment of rabbits with pertussis toxin resulted in complete loss of the ability of carbachol to inhibit isoproterenol-stimulated adenylate cyclase activity and cyclic AMP (cAMP) generation in the left atria. Under these circumstances, negative inotropic responses of the left atria to carbachol in the presence of forskolin and IBMX were only partially attenuated, suggesting that at least part of the reversal by carbachol of the positive inotropic responses to forskolin and IBMX occurs by a cAMP-independent mechanism. The same dose of pertussis toxin had a much greater inhibitory effect on the ability of carbachol to reverse the isoproterenol-stimulated positive inotropic response. The potassium channel blocker, 4-aminopyridine, had no effect on the ability of carbachol to inhibit isoproterenol-induced increases in cAMP levels in atria from saline-treated rabbits. 4-Aminopyridine produced a concentration-dependent attenuation of the inhibitory effect of carbachol on positive inotropic responses to forskolin and IBMX in the left atria from both saline and pertussis toxin pretreated rabbits. These results suggest that the ability of carbachol to open potassium channels contributes to the cAMP-independent component of the negative inotropic response to carbachol in the presence of forskolin and IBMX.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Effects of (+/-)- (+)- and (-)-metoprolol, (+/-)- (+)- and (-)-pindolol, (+/-)-mepindolol and (+/-)-bopindolol on the rat left atria and portal vein.

1. The effects of (+/-)- (+)- and (-)-metoprolol, (+/-)- (+)- and (-)-pindolol, (+/-)-mepindolol and (+/-)-bopindolol on the beta 1-adrenoceptor mediated responses of the rat left atria and the beta 2-adrenoceptor mediated responses of the rat portal vein to isoprenaline have been determined. 2. Racemic and (-)-metoprolol were selective beta 1-adrenoceptor antagonists. (+)-Metoprolol was devoid of beta-adrenoceptor antagonistic activity. 3. Racemic and (-)-pindolol were potent and (+)-pindolol was a modest beta-adrenoceptor antagonist. 4. (+/-)-Mepindolol and (+/-)-bopindolol were apparently competitive antagonists of the isoprenaline beta 1-adrenoceptor mediated responses of the rat left atria but non-competitive antagonists of the isoprenaline beta 2-adrenoceptor mediated responses of the rat portal vein. 5. It is suggested that (+/-)-mepindolol and (+/-)-bopindolol are slowly dissociating beta-adrenoceptor antagonists and the non-competitive antagonism can only be detected on tissues with modest receptor reserves for maximum responses to isoprenaline.

Adrenergic beta-Antagonists↗